Heart and Stroke Encyclopedia

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An artificial pacemaker is an electrical device implanted to keep a heart beating at the right speed and rhythm. It is needed when a person’s natural pacemaker either doesn’t work properly or the impulse is not transmitted adequately to the ventricles for the heart to contract. Pacemakers are typically used for hearts that beat too slowly or irregularly.

Patent ductus arteriosis is a congenital heart defect that allows blood to mix between the pulmonary artery and the aorta. Before birth an open passageway (the ductus arteriosus) exists between these two blood vessels, but it closes within a few hours of birth. When this doesn't happen, some blood that should flow through the aorta and out to the body returns to the blood vessels of the lungs. Patent ductus arteriosis is more common in premature infants than full-term babies.

PCI, an abbreviation for percutaneous coronary intervention that is also known as an angioplasty, is a medical procedure in which a balloon is used to open narrowed or blocked blood vessels of the heart (coronary arteries). With a PCI, a catheter with a deflated balloon on its tip is passed into the narrowed artery segment, the balloon is inflated and the narrowed segment widened. Then the balloon is deflated and the catheter is removed.

Percutaneous coronary intervention, or PCI, also known as an angioplasty, is a medical procedure in which a balloon is used to open narrowed or blocked blood vessels of the heart (coronary arteries). With a percutaneous coronary intervention, a catheter with a deflated balloon on its tip is passed into the narrowed artery segment, the balloon is inflated and the narrowed segment widened. Then the balloon is deflated and the catheter is removed.

Pericarditis is a condition in which there is inflammation of the sac-like covering of the heart (the pericardium). Pericarditis usually is caused by an infection, although it also can be caused by a heart attack, cancer, injury or surgery.

A peripheral angiogram is a test that uses X-rays to help your doctor find narrowed or blocked areas in one or more of the arteries that supply blood to your legs (View an animation of an angiogram). The test is also called a peripheral arteriogram.

Peripheral artery disease occurs when narrow arteries reduce blood flow to the limbs, mainly in the legs and feet. Symptoms can include pain in the legs or buttocks when exercising that goes away when the activity is stopped. Peripheral artery disease, often referred to as PAD, can be diagnosed with a quick, painless test called an ankle-brachial index test. Since it often goes undiagnosed, it's important to ask a healthcare professional to administer the test if you have symptoms.

Peripheral vascular disease is a narrowing and hardening of blood vessels carrying blood to the legs, feet and arms due to atherosclerosis. Peripheral artery disease, known as PAD, is a common form of peripheral vascular disease.

A PET scan of the heart is a noninvasive nuclear imaging test. It uses radioactive tracers (called radionuclides) to produce pictures of your heart. Doctors use cardiac PET scans to diagnose coronary artery disease (CAD) and damage due to a heart attack. PET scans can show healthy and damaged heart muscle. Doctors also use PET scans to help find out if you will benefit from a percutaneous coronary intervention (PCI) such as angioplasty and stenting, coronary artery bypass surgery (CABG) or another procedure.

Plaque is a buildup of cholesterol inside the wall of blood vessels. After years, plaque can become calcified and hard. It may also rupture. If this happens, a blood clot may form on the plaque and block blood flow, potentially causing a heart attack or stroke. The building up of plaque and hardening of the arteries is known as atherosclerosis.

A podiatrist is a doctor certified and trained to prevent, diagnose and treat conditions associated with the foot and ankle. Over time, people with diabetes tend to develop nerve damage in their feet and lower legs.

Polycythemia is an elevated number of red blood cells. It's also referred to as a high hematocrit or thick blood. Polycythemia is often seen in patients with lower-than-normal levels of oxygen in their blood.

Polyunsaturated fats may help lower blood cholesterol level when used in place of saturated fats. Polyunsaturated fat is mainly in vegetable oils such as corn, safflower, sunflower and soybean oils. It's usually liquid at room temperature. It is also found in seeds and fish.

A PET scan of the heart is a noninvasive nuclear imaging test. It uses radioactive tracers (called radionuclides) to produce pictures of your heart. Doctors use cardiac PET scans to diagnose coronary artery disease (CAD) and damage due to a heart attack. PET scans can show healthy and damaged heart muscle. Doctors also use PET scans to help find out if you will benefit from a percutaneous coronary intervention (PCI) such as angioplasty and stenting, coronary artery bypass surgery (CABG) or another procedure.

Potassium is an electrolyte found naturally in the body that works with sodium and calcium to regulate the body's water balance and maintain normal heart rhythm. It is responsible for nerve impulse conduction and muscle contraction. Found in many colorful fruits and vegetables, as well as low-fat dairy and certain types of seafood, natural sources of potassium play an important role in controlling blood pressure because potassium blunts the effects of sodium. The recommended daily intake of potassium for an average adult is about 4,700 milligrams per day.

Pre-diabetes is when your blood glucose (or sugar) levels are higher than normal, but not high enough to be diagnosed as diabetes. Blood testing may reveal impaired fasting glucose or impaired glucose tolerance. People with pre-diabetes are at increased risk for developing type 2 diabetes, heart disease and stroke.

Prinzmetal angina can also be called, variant angina, Prinzmetal's variant angina, angina inversa. Unlike typical angina – which is often triggered by exertion or emotional stress - Prinzmetal’s angina almost always occurs when a person is at rest, usually between midnight and early morning. These attacks can be very painful. The pain from variant angina is caused by a spasm in the coronary arteries (which supply blood to the heart muscle).

The spasms tend to come in cycles – appearing for a time, then going away. After six to 12 months of treatment, doctors may gradually reduce the medication.

Progestin is any of a group of steroid hormones that have the effect of the female hormone progesterone. It's used in oral contraceptives and hormone replacement therapy. There is also a natural form of progestin.

A prostaglandin is one of several hormone-like substances that participate in a wide range of body functions. For example, it's involved in contracting and relaxing smooth muscle; dilating and constricting blood vessels; control of blood pressure; and modulation of inflammation. Prostaglandins are derived from a chemical called arachidonic acid.

Pulmonary artery catheterization is used to evaluate primary pulmonary hypertension. In the procedure, a thin, flexible tube called a Swan-Ganz catheter is usually inserted in one of the veins in the neck and threaded into the right ventricle and pulmonary artery. This is a common way to measure the pressure in the pulmonary artery and find out what treatment is appropriate. It's also used in critically ill patients to provide continuous monitoring of heart function. It is sometimes called Swan-Ganz catheterization.

A pulmonary atresia is a congenital heart defect in which no pulmonary valve exists. Blood can't flow from the right ventricle into the pulmonary artery and on to the lungs. This results in a blue discoloration of the skin (called cyanosis).

Pulmonary edema is fluid buildup in the lung. It's usually due to mitral stenosis or left ventricular failure. Symptoms of pulmonary edema include difficulty breathing, coughing up blood-tinged sputum, excessive sweating, anxiety and pale skin.

Pulmonary hypertension is high blood pressure in the arteries, capillaries and veins within the lungs. This condition is different from hypertension, or high blood pressure, measured by a traditional test with a cuff around your arm. Pulmonary hypertension causes the right side of the heart to work harder due to higher pressures. This increased pressure may be detected by heart sounds heard via a stethoscope or bulging neck veins. Warning signs for pulmonary hypertension include fatigue, dizziness and shortness of breath.

Pulmonary regurgitation (PR, also called pulmonic regurgitation) is a leaky pulmonary valve. This valve helps control the flow of blood passing from the heart to the lungs. A leaky pulmonary valve allows blood to flow back into the heart chamber before it gets to lungs for oxygen.

Pulmonary stenosis is a congenital heart defect in which the pulmonary valve doesn’t open properly. The pulmonary valve is between the right ventricle and the pulmonary artery. It opens to allow blood to flow from the right ventricle through the pulmonary artery to the lungs. This forces the right ventricle to pump harder than normal to overcome the obstruction. In most children, the obstruction can be relieved by a procedure called balloon valvuloplasty. Others may need open-heart surgery.

Pulse is also called heart rate. It's the number of times your heart beats per minute. Normal heart rate varies from person to person and is normally 60 to 100 times a minute. The best places to find your pulse are the wrists, the inside of your elbow, the side of your neck and the top of the foot. To get the most accurate reading, put your finger over your pulse and count the number of beats in 60 seconds.

*All health/medical information on this website has been reviewed and approved by the American Heart Association, based on scientific research and American Heart Association guidelines. Use this link for more information on our content editorial process.